设置图片备选文字
提示文字会在图片无法正常加载时候显示
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>网页标题</title>
</head>
<body>
<img src="./images/一张不存在的图片.jpg"
width="888" height="444" alt="图片错误,请刷新页面">
</body>
</html>
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>网页标题</title>
</head>
<body>
<img src="./images/一张不存在的图片.jpg"
width="888" height="444" alt="图片错误,请刷新页面">
</body>
</html>